We have undertaken projects aimed at characterization of the genome of Plasmodium. Along with the development of polymorphic genetic markers, we have studied the arrangement of particular segments of the genome: (1) genes for stable RNA's, ribosomal RNA, 5S and rRNA (2) DNA that apparently does not code for RNA (3) DNA that codes for defined proteins. We have mapped, by restriction enzyme analysis, the four ribosomal genes of P. berghei. They are not tandemly arranged and in this way, look more like E. coli genes than genes from a eucaryotic organism. The rRNA and 5S genes also appear to be arranged in a manner similar to that found in a procaryotic organism. We have also discovered a segment of the genome whose sequence suggest that it does not code for a protein of any size. Initially, it appears to be highly repeated and regularly dispersed throughout the genome but not in the vicinity of the stable RNA genes. Finally, we are searching for coding regions of the plasmodium genome by using defined cloned probes for other systems as well as developing probes directly from plasmodium.